Changes in neuronal activity are accompanied by the release of vasoactive mediators that cause microscopic dilation and constriction of the cerebral microvasculature and are manifested in macroscopic blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signals. We used two-photon microscopy to measure the diameters of single arterioles and capillaries at different depths within the rat primary somatosensory cortex. These measurements were compared with cortical depth-resolved fMRI signal changes. Our microscopic results demonstrate a spatial gradient of dilation onset and peak times consistent with "upstream" propagation of vasodilation toward the cortical surface along the diving arterioles and "downstream" propagation into local capillary beds. The observed BOLD response exhibited the fastest onset in deep layers, and the "initial dip" was most pronounced in layer I. The present results indicate that both the onset of the BOLD response and the initial dip depend on cortical depth and can be explained, at least in part, by the spatial gradient of delays in microvascular dilation, the fastest response being in the deep layers and the most delayed response in the capillary bed of layer I.blood flow | cortical layer | hemodynamic | imaging | somatosensory N euroglial activation is accompanied by release of vasoactive mediators that dilate and constrict the surrounding arterioles (1, 2) and capillaries (3, 4). These changes in diameter in turn lead to changes in blood flow throughout the vascular matrix and can be detected on the macroscopic level as a positive blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signal when blood flow response exceeds oxygen consumption (5-7). Under the assumption of local neurovascular coupling, the onset of the changes in diameter is determined by the following three factors, any of which may differ as a function of the cortical depth and branching order within the vascular tree: (i) the onset and peak time of the neuronal activity evoking the response; (ii) the time needed to release a vascular messenger [e.g., prostaglandin or NO (8)]; and (iii) the time needed for the target vessel to respond. However, in addition to local neurovascular coupling, vascular responses can propagate within the arteriolar/capillary networks (3, 9, 10). Indeed, propagation of dilation and constriction has been observed on the cortical surface (11-15), in excised cerebral vessels, and in noncerebral preparations (16,17).Previous studies with single-vessel resolution in vivo have been limited to the cortical surface, but recent improvements in twophoton microscopy technology allow direct imaging of singlevessel diameters and flow velocities within a 3D geometry of vascular trees (1,2,18,19). In the present study, we used this technology to examine microvascular responses to sensory stimulation down to 550 μm below the cortical surface in the rat primary somatosensory cortex (SI). We then compared the results with highresolution BOLD fMRI to investigate the extent to which laminar ...

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Objective: It was the aim of this study to investigate the surface temperature in newborns within the first hour after delivery. Furthermore, the influence of different environmental conditions with regard to surface temperature was documented. Methods: Body surface temperature was recorded under several environmental conditions by use of infrared thermography. 42 newborns, all delivered at term and with weight appropriate for date, were investigated under controlled conditions. Results: The surface temperature immediately after birth shows a uniform picture of the whole body; however, it is significantly lower than the core temperature. Soon after birth, peripheral sites become cooler whereas a constant temperature is maintained at the trunk. Bathing in warm water again leads to a more even temperature profile. Radiant heaters and skin-to-skin contact with the mother are both effective methods to prevent heat loss in neonates. Conclusions: Infrared thermography is a simple and reliable tool for the measurement of skin temperature profiles in neonates. Without the need of direct skin contact, it may be helpful for optimizing environmental conditions at delivery suites and neonatal intensive-care units.

Our cases support the assumption of familiality in CCHS although the mode of inheritance remains to be clarified. Polygraphic recordings including capnography should be performed in siblings of CCHS patients early in life in order to avoid secondary complications. Noninvasive treatment by ventilation via special face masks is feasible.

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